Abstract:

An environmental assessment of the cumulative effects of implementing agricultural (mainly rice crop) and forestry projects in the Miriñay River Basin, an area of growing economic activity located in Corrientes Province (Argentina), was performed. Increment of water consumption and loss of natural environments related to both implemented projects and potential future expansions were considered. Land-use maps for years 2000 and 2014 were produced based on satellite images. A hydrological model was developed and calibrated based on hydrometric data, and later used to simulate a natural scenario, representing the conditions previous to human impacts of the land use changes, and three expansion scenarios for agriculture and forestry (short term, middle term, and long term), including the construction of new dams for irrigation. An annual water balance indicator was built based on the model results. Non-natural areas constituted 12.9[%] of the basin in 2014, including 114,260 ha of rice/pastures, 15,058 ha of dams for irrigation, and 26,745 ha of forestry. Comparing the water balance indicator for the present conditions withthe one for the natural scenario, variations of different sign and magnitude were otained for the different sub-basins, with reductions which do not exceed 8[%]. In turn, comparing the water balance indicator for future scenarios with the one for the present one, a maximum reduction of about 10[%] was obtained, which is considered relatively small. From the analysis of losses of natural environments for the three future scenarios it was observed that, although no critical conditions would be attained at the basin scale for all of them, some degree of criticality would be reached for three sub-basins in the case of the long-term scenario. In order to avoid those critical conditions, allowing the development of sustainable production without jeopardizing the conservation of natural environments, an integrated land-use management policy is proposed, through the regulation of the maximum percentage of land use change.